The present invention relates to coffee grinders and, more particularly, to coffee grinders having a component for the suppression of fines generated by the grinder action of the mechanism for grinding the coffee beans into ground coffee.
Apparatus for grinding coffee beans into ground coffee have found significant consumer acceptance, probably due to the perceived freshness of the coffee produced with recently ground coffee. Many commercial establishments use combinations of coffee grinders and brewers or a single unit having the combined features to produce coffee of the freshness now being demanded by the consumer. Grocery chains have long recognized that many discerning coffee drinkers prefer to grind their own coffee at the store and thus have provided coffee beans and the necessary apparatus for the self grinding of the beans into ground coffee. The roasted coffee bean, however, produces along with the particles of ground coffee a very fine powder, primarily bean husk, called chaff fines that tends to float and separate from the main stream of ground coffee that emerges from the coffee grinder. During grinding, some of the chaff becomes lodged against underlying exterior surfaces of the grinder and adheres to the exposed surfaces of the grinder and associated equipment. Applicants have determined that the problem is largely due to electrostatic attraction of the exposed surfaces of the grinder to the chaff fines and has noted the problem to be particularly exacerbated when the grinder is used under extremely dry conditions such as heated facilities during the winter months. Moreover, where a coffee brewer is in close vicinity to the grinder as in the combination of a grinder and brewer in the same apparatus, a gummy substance produced by the moisture from brewing coming into contact with the chaff fines adhering to the apparatus wall is produced. Frequent cleaning is required in order to provided for a clean appearance and proper functioning of the apparatus.
A number of devices are described in the prior art that claim to reduce the frequency of cleaning of grinders due to chaff generation. As examples of such devices, reference is first made to U.S. Pat. Nos. 4,813,622 and 5,042,731, both assigned to the Bunn-O-Matic Corporation and describing a coffee grinder unit with a discharge chute unit of the type typically found in grocery stores. The units are provided with a chaff fine suppressor in the form of lever-like member. The member is attached to the discharge unit immediately adjacent the opening into the grinder. The chaff fine suppressor in each of the aforementioned patents serves mainly to physically prevent the coffee chaff fines from separating from the main stream of coffee grounds. To some extent as determined by applicants, the chaff springs, when made of a conducting material and electrically grounded, may also serve to dissipate a portion of the electrostatic charge imparted to the stream of ground coffee particles, including the chaff fines. Still another example of a chaff spring is found in U.S. Pat. No. 5,201,474 also assigned to the Bunn-o-Matic Corporation. The grinder described in this patent has a component associated with the grinding burrs that, according to the patentee, functions to keep the chaff fines within the ground coffee stream. A further example is noted in U.S. Pat. No. 5,244,414 assigned to the Grindmaster Corporation wherein a problem associated with the moisture created in proximity of the chaff fines is described. A moisture prevention valve is described that closes the opening to the grinder immediately above the brew basket during the brewing operation. This closing of the opening prevents the moisture from the brewing operation from seeping back into the chute from the grinder area and being absorbed by the coffee in the chute and grinding mechanism. It also tends to prevent the moisture from coming into contact with the chaff fines that may have accumulated on the walls of the apparatus. The moisture tends to clump the ground coffee and particles together in a larger mass that does not readily flow. While the inventions described in each of the aforementioned patents function to lessen the problems associated with chaff fines, the problem of chaff collection on the surrounding walls of the apparatus is nevertheless still prevalent to a significant degree, resulting in significant downtime during cleaning periods, unsightly appearance, and interference with the grinding operation. There are many who believe that the chaff left from previous grinding operations unfavorably distorts the flavor of coffee made from ground coffee of subsequent grinding operations.
As stated above, applicants have determined through a thorough investigation that a significant amount of chaff fines accumulate on the exterior surfaces of the grinder due to the presence of an electrostatic charge on the stream of particles produced during the grinding operation. Despite the use of chaff springs of the prior art, even when incidentally made conducting and electrically grounded, the charge on the stream remains to a large extent as evidenced by the large amount of chaff fines that clings to the surrounding surfaces of the apparatus. The chaff fines, being of less mass and dimensionally much smaller than the grounds, are significantly affected by the charge formed on the chaff fines during the grinding. The chaff fines are repelled by the similar charge carried by the stream of ground coffee and separate from the stream. The ground coffee, being coarser and thus much larger is unaffected by the charge and proceeds downwardly. The chaff fines under the influence of the charge becomes repelled by the stream and is attracted by the opposite charge lying on the surrounding surfaces of the apparatus induced by the charge on the stream of ground coffee. This lead applicants to determine that a continuous and substantial neutralization of the electrostatic charge imparted to the ground coffee and chaff fines following the grinding operation would significantly minimize the accumulation of chaff fines on the exterior surfaces, thereby resulting in the reduction in the frequency of cleaning needed by operating personnel and minimize the other objections created by the presence of chaff. Applicants then set about to implement their findings, namely, devising components that more effectively dissipate the electrostatic charge given to the stream of material, including the chaff fines.
It is therefore a paramount object of the present invention to further reduce the frequency and duration of cleaning apparatus for the grinding of materials where chaff fines from the grinding process accumulate on the exterior surfaces of the grinding apparatus due to the induced electrostatic charge on the ground particles exiting the grinder.
It is still a further object of the present invention to provide for a simple but efficient mechanical component associated with a grinder that effectively reduces or neutralizes the induced electrostatic charge imparted to particles comprising the stream of material exiting the grinder.
It is yet a further object of the present invention to provide for a mechanism combined with the functions of a chaff spring that more effectively reduces the electrostatic charge imparted to the stream of material including chaff fines.
These and other objects will become readily apparent and met through a reading of the description of the present invention along with the drawings described below.